[unreadable] This research involves the development of a method to quantify regional flow in tissues using automated instrumental procedures. Phase I results have demonstrated that fluorescent antibodies, specific to antigens in capillary endothelium, can be spatially located in sequential fluorescence images recorded from frozen tissue blocks during organ serial sectioning. Statistical limitations imposed on fluorescent and radioactive microsphere methods are removed by the use of molecules as flow markers (molecular microspheres), greatly expanding the details of organ-flow maps. During Phase I, fluorescent antibodies were identified that have excellent retention in heart vascular systems and regional deposition which correlates strongly with simultaneously injected 15 micron-diameter flourescent microspheres. Both the validity of the molecular microsphere approach and the feasibility of the imaging methodology have been demonstrated. Phase II will concentrate on in vivo studies in heart, development of analysis procedures and validation studies in lung and brain to be undertaken by collaborators. Methods will also be developed to conduct multiple flow measurements in the same organ. This project will provide researchers with methods and instrumentation to measure regional flow in tissue volumes much smaller than those possible with current techniques. [unreadable] [unreadable]